In recent years, it has become common to use carbon dioxide (CO2) gas as a contrast agent in angiography. CO2 works well as a contrast agent and, unlike iodine which can cause complications for some patients, CO2 is well tolerated by nearly all patients. In addition, CO2 is inexpensive and, because of its high solubility, quickly leaves the body through normal respiration.
CO2 is typically delivered to the body through a gas delivery system that can, for example, comprise a CO2 source such as a bag filled with the gas, a delivery means such as a syringe or pump, and a catheter. Unfortunately, it is possible for leaks to develop in such a system that enable air to enter system and, therefore, the patient. While the oxygen gas within air is relatively harmless, the nitrogen gas within the air can cause serious health problems, including ischemia. Therefore, it is important when performing CO2 angiography to ensure that air does not enter the gas to be delivered to the patient. Although systems and methods have been proposed for detecting such contaminants, none are presently known that are simple, inexpensive, and immediate.